Microtubules are hollow polymers made up of tubulin subunits. Neurons, like other eukaryotic cells, contain a pool of free tubulin subunits and a pool of the microtubule polymers. These two pools dynamically exchange with one another such that microtubules undergo bouts of assembly and disassembly.n neurons, microtubules are also nucleated at the centrosome (located in the cell body of the neuron), but the microtubules are then severed from the centrosome so that they can be deployed into axons and dendrites.
If the parent makes this election, the child does not have to file a return. Earned and Unearned Income. If a child has both earned and unearned income, he or she must file a return (2016 and 2015) if: unearned income was over $1,050; earned income was over $6,300, or
You must file a federal income tax return for any tax year in which your gross income is equal to or greater than the personal exemption amount and standard deduction combined (per the Form 1040 Instructions for the corresponding tax year). Generally, you need to file returns going back six years. Copy: You can request a copy of your tax return, but in most cases you must pay a fee to do so (currently $50). 2  Use Form 4506, Request for Copy of Tax Return (PDF), to request a copy of your tax return. 3  Copies of Forms 1040, 1040A, and 1040EZ are generally available for 7 years from the date you filed the return.